General
Ventimental calculates airflow rates for mechanical ventilation systems using the methodologies of Section 6.2 — Ventilation Rate Procedure — of ASHRAE Standard 62.1, Ventilation and Acceptable Indoor Air Quality.
Multiple Zone Systems
For multiple‑zone systems, both constant air volume (CAV) and variable air volume (VAV), Ventimental calculates the required outdoor air ventilation rate using either the simplified method (ASHRAE 62.1 Section 6.2.4.3) or the alternative procedure (ASHRAE 62.1 Normative Appendix A).
Ventilation Rates
The outdoor air ventilation rates of ASHRAE 62.1 Table 6‑1 (Minimum Ventilation Rates in Breathing Zone) and the exhaust air ventilation rates of ASHRAE 62.1 Table 6‑2 (Minimum Exhaust Rates) are combined in a single table. For example, if “Art Classroom” is selected for a zone, both the Table 6‑1 outdoor air rate and the Table 6‑2 exhaust air rate for “Art Classroom” are calculated.
In addition to the ventilation rates of Tables 6‑1 and 6‑2, the ventilation rates for Outpatient Health Care Facilities of ASHRAE 62.1 Normative Appendix D Table D‑1 are included.
Zone Templates
Zone templates can be created and assigned to multiple zones, such that the inputs for the zone template (floor area, occupancy type, Ez, etc.) become the default inputs for those zones. This reduces data entry and improves consistency for projects with multiple identical spaces such as small offices, classrooms, and restrooms.
Input
Zones are input on worksheets separate from the supply fans and exhaust fans, and each zone is assigned to a supply fan and/or an exhaust fan. This methodology allows for easily switching zone assignments from one fan to another.
Risers
Risers indicate the cumulative airflow rate between the floors of the building for fans that serve more than one floor.
Risers are created automatically for each fan, where the floor a zone is assigned to is based on the initial characters of the zone numbers (as defined by the user).
Riser airflow can be upward (supply fan at the bottom or exhaust fan at the top), downward (supply fan at the top or exhaust fan at the bottom), or both upward and downward (supply or exhaust fan located in the middle of the riser).
Groups
Multiple fans can be grouped, allowing the cumulative airflow rates of groups of fans to be analyzed.
Critical Zones
Critical zones are highlighted for multiple‑zone systems, simplifying the analysis and adjustment of inputs necessary to optimize outdoor airflow rates.
Transfer Air
Ventimental supports the transfer of air from zones provided with outdoor air ventilation (or where outdoor air exceeds exhaust air) to zones provided with exhaust air ventilation (or where exhaust air exceeds outdoor air).
Two methods of air transfer are supported: direct zone‑to‑zone transfer and indirect transfer via plenums. Indirect transfer is necessary where air from a zone must be transferred to more than two zones, because each zone can transfer air directly to only two other zones.
Plenums can represent building volumes (above‑ceiling spaces, chases, etc.), passive or fan‑forced transfer air ductwork systems, or air volumes between zones (such as door undercuts).
Features
- Supports both Inch‑Pound (I‑P) and International System (SI) units.
- 480 zones.
- 30 zone templates.
- 30 supply fans.
- 30 exhaust fans.
- 8 user‑defined zone air distribution effectiveness factors (in addition to those in ASHRAE 62.1).
- 16 user‑defined zone ventilation rates (in addition to those in the Standard).
- Risers for each fan and for 5 groups of fans, up to 10 floors.
- Direct zone‑to‑zone air transfer and indirect air transfer via plenums.
- Metrics for analyzing and optimizing 100% outdoor air ventilation systems.
- All of the data is editable!
Limitations
Neither the ASHRAE 62.1 Section 6.3 Indoor Air Quality (IAQ) Procedure nor the Section 6.4 Natural Ventilation Procedure are supported.
Air change rate methodologies are not supported. Accordingly, the ventilation rate calculation methodologies of ASHRAE Standard 170 (Ventilation of Health Care Facilities) are not supported.
Though Ventimental tracks the relative pressure of each zone (whether net positive, net negative, or neutral), the pressure relationships between zones are not tracked.